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PRODUCTION GUIDELINES
The LC modules are packaged in a hybrid SMD package that supports hand- or
automated-assembly
techniques.
Since
LC
devices
contain
discrete
components internally, the assembly procedures are critical to ensuring the
reliable function of the LC product. The following procedures should be reviewed
with and practiced by all assembly personnel.
PAD LAYOUT
The following pad layout diagrams are designed to facilitate both hand and
automated assembly.
RECEIVER HAND ASSEMBLY
The LC-S Receiver’s primary mounting
surface is sixteen pads located on the
bottom of the module. Since these pads
are
inaccessible
during
mounting,
castellations that run up the side of the
module have been provided to facilitate
solder wicking to the module's under-
side. If the recommended pad place-
ment has been followed, the pad on the
board will extend slightly past the edge
of the module. Touch both the PCB pad
and the module castellation with a fine
soldering tip. Tack one module corner
first, then work around the remaining
attachment points using care not to
exceed the times listed below.
Castellations
PCB Pads
Soldering Iron
Tip
Solder
Absolute Maximum Solder Times
Hand-Solder Temp. TX +225°C for 10 Sec.
Hand-Solder Temp. RX +225°C for 10 Sec.
Recommended Solder Melting Point +180°C
Reflow Oven: +220° Max. (See adjoining diagram)
AUTOMATED ASSEMBLY
For high-volume assembly most users will want to auto-place the modules. The
receivers have been designed to maintain compatibility with reflow processing
techniques; however, due to the module's hybrid nature certain aspects of the
assembly process are far more critical than for other component types.
Following are brief discussions of the three primary areas where caution must be
observed.
Reflow Temperature Profile
The single most critical stage in the automated assembly process is the reflow
process. The reflow profile below should be closely followed since excessive
temperatures or transport times during reflow will irreparably damage the modules.
Assembly personnel will need to pay careful attention to the oven's profile to
ensure that it meets the requirements necessary to successfully reflow all
components while still meeting the limits mandated by the modules themselves.
Shock During Reflow Transport
Since some internal module components may reflow along with the components
placed on the board being assembled, it is imperative that the module not be
subjected to shock or vibration during the time solder is liquidus.
Washability
The modules are wash resistant, but are not hermetically sealed. They may be
subject to a standard wash cycle; however, a twenty-four-hour drying time
should be allowed before applying electrical power to the modules. This will allow
any moisture that has migrated into the module to evaporate, thus eliminating the
potential for shorting during power-up or testing.
125
oC
60
0
0
50
100
150
200
250
300
120
180
240
300
30
90
150
210
270
330
360
180
oC
210
oC
220
oC
Time (Seconds)
Ideal Curve
Limit Curve
Forced Air Reflow Profile
1-1.5 Minutes
2-2.3 Minutes
Ramp-up
Preheat Zone
Cooling
Soak Zone
Reflow Zone
20-40 Sec.
2 Minutes Max.
Figure 12: Required Reflow Profile
Revision 2 - 11/98
Figure 11: LC-S Soldering Technique
Figure 10: Recommended Pad Layout
0.100"
0.310"
0.100"
0.070"
.100
0.150
.070
0.775
TX Layout Pattern Rev. 2
(Not to Scale)
LC-P RX Layout Pattern Rev. 3
Pinned SMD Version
(Not to Scale)
LC-S RX Layout Rev. 1
Compact SMD Version
(Not to Scale)
0.100"
0.070"
0.065"
0.610"
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